Fluid management pump systems are employed during surgical procedures to introduce sterile solution into surgical sites. For example, a fluid management pump may be employed during an endoscopic surgical procedure. In endoscopic surgery, an endoscope is inserted into the body through a small opening known as a portal. The endoscope is positioned at the site where the surgical procedure is to be performed. The endoscope is a surgical instrument that provides a view of the portion of the body in which it is inserted. Other surgical instruments are placed in the body through-other portals and are positioned at the surgical site. The surgeon views the surgical site through the endoscope in order to determine how to manipulate the other surgical instruments. The development of endoscopes and their companion surgical instruments has made it possible to perform minimally invasive surgery that eliminates the need to make large incisions to gain access to the surgical site. An advantage of performing endoscopic surgery is that, since the portions of the body that are cut open are minimized, the portions of the body that need to heal are likewise reduced. Still another advantage of endoscopic surgery is that it exposes less of the patient's internal tissues and organs to the open environment. This minimal opening of the patient's body lessens the extent to which these internal tissues and organs are exposed to infection.
The ability to perform endoscopic surgery is enhanced by the development of fluid management pumps. A fluid management pump pumps a sterile solution into the enclosed portion of the body at which the endoscopic surgical procedure is being performed. This pressure of this solution expands, distends, and separates the tissue at the surgical site so as to increase both the field of view of the site and the space available to the surgeon for manipulating the instruments. One type of endoscopic surgery in which fluid management pumps have proven especially useful is in arthroscopic surgery. In arthroscopic surgery, a specially designed endoscope, called an arthroscope, is employed to examine inter-bone joints and the ligaments and muscles that connect the bones. A fluid management pump is often employed in arthroscopic surgery to expand the space between the bones and adjacent soft tissue in order to increase the field in which the surgeon can perform the intended surgical procedure. Fluid management pumps are, during arthroscopic surgery, used to increase the surgical view and working space around the joints that form an elbow, a knee, a wrist or an ankle. During arthroscopic surgery, the pressure of the fluid introduced by the pump also reduces and contains the internal bleeding at the surgical site. Moreover, fluid management pumps are used in both endoscopic surgery and in other surgical procedures to remove debris generated by the procedure.
The Applicant's U.S. Pat. No. 5,810,770, entitled FLUID MANAGEMENT PUMP SYSTEM FOR SURGICAL PROCEDURES, issued Sep. 22, 1998, and incorporated herein by reference, discloses one conventional fluid management pump system. This particular system includes a pump that is used to force sterile solution to the surgical site. The pump is part of a tube set that includes a inflow line through which the fluid flows from the pump to the patient. The tube set also includes a second line, an outflow line, through which the fluid discharged from the surgical site is flowed to a collection container. The tube set has a third line for receiving a fluid column from the surgical site. The head of the fluid column in the third line is applied to a transducer which, in turn, generates a signal representative of the fluid pressure at the surgical site. This system also includes a control console to which the tube set is connected. In this particular system, the pressure transducer is located in the control console. The control console converts the line voltage into a signal suitable for energizing the pump. The control console also includes a pair of solenoids, each one of which is in close proximity with a separate one of the fluid inflow or outflow lines. Each solenoid regulates the open/closed state of a valve associated with a separate one of the inflow or outflow conduits.
The control console also includes a number of switches that allows the surgeon to regulate the fluid pressure and the rate of fluid flow through the surgical site. Based on the surgeon-set commands and the sensed fluid pressure at the surgical site, the control console selectively energizes the pump and opens and closes the inflow and outflow conduits.
While the above described fluid management pump systems work reasonably well, there are some disadvantages associated with their use. In particular, this type of system brings additional equipment, additional clutter, to the surgical suite. Moreover, many current fluid management systems are designed so that the control switches that are actuated to establish fluid flow rate and fluid pressure are mounted on the control console. This means that, when a surgeon wants to reset these settings, he/she must either personally be divert attention from the instruments and the surgical site in order to depress the buttons on the control console, or instruct an assistant to enter the new settings. There have been attempts to minimize this disruption by providing control consoles with separate hand controllers. This type of controller is connected to its associated console by a cable. While this type of remote controller works reasonably well, it brings another device and a complementary control line, both additional clutter, to the surgical suite. Moreover, as with any piece of reusable medical equipment, it is necessary to maintain these consoles and even sometimes necessary to repair them.
The cannulae with which many current fluid management pump systems are used also have their own shortcomings which detract from the utility of these systems. These cannulae are the rigid members that are inserted into the portals formed in the patient's body and that serve as the conduits through which the irrigating fluid is introduced into and drained from the surgical site. In practice, it is often necessary to provide three separate conduits to the associated tube set. A first conduit serves as the flow path through which fluid is introduced into the surgical site. A second conduit serves as the flow path through which fluid is discharged from the surgical site. Finally, there is a third conduit over which a column of fluid is withdrawn from the surgical site. This is fluid column that is applied to the complementary transducer in order to determine the fluid pressure at the surgical site. These cannulae, in addition to providing fluid conduits, also serve as the conduits through which instruments such as the endoscope/arthroscope are seated at the surgical site.
The problem associated with many of these cannulae is that the fluid flowing through them undergoes a significant pressure drop. For example, studies have shown that in a system designed to apply approximately 1.8 lit./min fluid flow, it is necessary to pump the fluid out of the pump at a pressure of approximately 18 psig in order to maintain the fluid at the surgical site at a constant pressure. Of this 18 psig of pressure, approximately 15 psig are lost in a pressure drop across one of the cannula. Thus, a significant amount of the power that is developed by the pump is expended in order to simply force the fluid through the cannulae. This means that large amounts of energy are applied to the pump solely to overcome this cannula-centered pressure drop. Consequently, it has been necessary to provide current control consoles with power converters that can deliver the large quantities of energy required by these pumps. The size of these power converters has contributed to making current control consoles, heavy, bulky pieces of equipment. Moreover, these power converters can significant amounts of waste heat.
Moreover, sometimes during a surgical procedure the outflow of fluid from the surgical site can be temporarily blocked. When this flow is so blocked, the pressure of the fluid output by the pump is not simply lost across the cannula. Instead, the pressure of this fluid will be up at the surgical site. If this pressure becomes too great, there is risk that the patient's tissue may become damaged.